In surgical interventions, it is frequently required to spread tissue in order to provide access to body structures situated below the tissue to be spread. In particular, in many heart, thorax and spinal surgeries, the sternum is divided longitudinally; the two parts of the sternum are then spread from each other, thus opening up the thorax in order to enable the surgeon to perform surgery inside or through the chest cavity.
For spreading and holding tissue, surgical retractors are employed. Such a retractor usually comprises at least two tissue holding members and a support structure. The tissue holding members are designed for engaging with the tissue, in particular with the edges created by dividing the tissue, and are arranged in an opposing relationship on the support structure. The support structure serves to support the tissue holding members and comprises a drive mechanism for spreading the opposing tissue holding members from each other in order to spread the tissue edges from each other. In use, the support structure may be placed on the body surface, with the tissue holding members extending into the body and into the cavity to be kept open.
A particular retractor for performing heart and thorax surgeries is disclosed in DE 200 03 335 U1. The known retractor comprises a rail, a first arm protruding from the rail at an angle and a second arm extending approximately parallel to the first arm. The arms are equipped with blades for insertion into a cavity and for holding tissues on both sides of the cavity. The blades extend in a direction substantially transverse to the arms and to the rail. The distance between the two arms can be modified in order to spread the tissues, providing space for performing a surgical intervention.
According to DE 200 03 335 U1, the blades are pivotably mounted within a blade holder, the blade holder being freely movable along a respective arm. When the blades are engaged with tissue, the blade holder is blocked against movement along the arm by the counter-force exerted by the tissue on the blade. In this way, the positions of the blades can be easily adjusted to a particular surgical situation.
However, the tissues to be spread may not always be adequately held by blades which extend perpendicular or transverse to the directions of the holding arms and the rail. While such blades may be optimal in one surgical situation, it may be necessary to exert a holding force in a different direction on a particular piece of tissue in another situation. Such a situation may arise during a surgical intervention in a foreseeable or in a not foreseeable manner. The requirement of an obliquely directed holding force may arise, e.g., also due to lifting one side of the tissue for better accessing or viewing organs on that side.